Replace Boost.Dll with our own function

Now we no longer rely on anything from Boost. Later we'll move the path
detection to the very beginning of the plugin bridge initialization so
it can be set from the coming chainloader libraries.

src/common/linking.cpp

@@ -0,0 +1,58 @@
+// yabridge: a Wine VST bridge
+// Copyright (C) 2020-2022 Robbert van der Helm
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+#include "linking.h"
+
+#include <cassert>
+
+#include <dlfcn.h>
+
+std::string get_this_file_location() {
+    // We'll try to find the library this function was defined in. When called
+    // from a copy of `libyabridge-*.so` this will return that library. Because
+    // the chainloader libraries load the plugin libraries from fixed locations,
+    // the plugin libraries cannot use this function directly when using the
+    // chainloaders.
+
+    // On success this returns a non-zero value, just to keep you on your toes
+    Dl_info info;
+    assert(dladdr(reinterpret_cast<void*>(get_this_file_location), &info) != 0);
+    assert(info.dli_fname);
+
+    std::string this_file(info.dli_fname);
+
+    // HACK: Not sure why, but `boost::dll::this_line_location()` used to return
+    //       a path starting with a double slash on some systems. I've seen this
+    //       happen on both Ubuntu 18.04 and 20.04, but not on Arch based
+    //       distros.  Under Linux a path starting with two slashes is treated
+    //       the same as a path starting with only a single slash, but Wine will
+    //       refuse to load any files when the path starts with two slashes. The
+    //       easiest way to work around this if this happens is to just add
+    //       another leading slash and then normalize the path, since three or
+    //       more slashes will be coerced into a single slash. We no longer use
+    //       Boost.Dll, but unless this was an obscure Boost.Filesystem bug it
+    //       sounds more likely that it was caused by some `ld.so` setting.
+    //       Unless we can really figure out what was causing this, it seems
+    //       best to still account for it
+    if (this_file.starts_with("//")) {
+        const size_t path_start_pos = this_file.find_first_not_of('/');
+        if (path_start_pos != std::string::npos) {
+            this_file = "/" + this_file.substr(path_start_pos);
+        }
+    }
+
+    return this_file;
+}

src/common/linking.h

@@ -0,0 +1,32 @@
+// yabridge: a Wine VST bridge
+// Copyright (C) 2020-2022 Robbert van der Helm
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+#pragma once
+
+// This header is completely standalone so the chainloading libraries can
+// retrieve their file path without pulling in a lot of additional dependencies
+
+#include <string>
+
+/**
+ * Return a path to this `.so` file. This can be used to find out from where
+ * this copy of `libyabridge-{vst2,vst3}.so` or `libyabridge-chainloader-*.so`
+ * was loaded so we can search for a matching Windows plugin library. When the
+ * chainloaders are used, this path should be passed to the chainloaded plugin
+ * library using the provided exported functions since they can't detect the
+ * path themselves.
+ */
+std::string get_this_file_location();

src/plugin/bridges/common.h

@@ -29,6 +29,9 @@
 #include "../../common/utils.h"
 #include "../host-process.h"
 
+// FIXME: This should be passed as an argument instead
+#include "../../common/linking.h"
+
 /**
  * If the amount of lockable memory is below this, then we'll warn about it
  * during startup. Otherwise we may run into issues when mapping shared memory
@@ -73,9 +76,8 @@ class PluginBridge {
      * @throw std::runtime_error Thrown when the Wine plugin host could not be
      *   found, or if it could not locate and load a VST3 module.
      */
-    template <invocable_returning<TSockets,
-                                  asio::io_context&,
-                                  const PluginInfo&> F>
+    template <
+        invocable_returning<TSockets, asio::io_context&, const PluginInfo&> F>
     PluginBridge(PluginType plugin_type, F&& create_socket_instance)
         // This is still correct for VST3 plugins because we can configure an
         // entire directory (the module's bundle) at once

src/plugin/meson.build

@@ -9,6 +9,7 @@ vst2_plugin_sources = files(
   '../common/logging/common.cpp',
   '../common/logging/vst2.cpp',
   '../common/audio-shm.cpp',
+  '../common/linking.cpp',
   '../common/plugins.cpp',
   '../common/process.cpp',
   '../common/utils.cpp',
@@ -80,6 +81,7 @@ vst3_plugin_sources = files(
   '../common/serialization/vst3/process-data.cpp',
   '../common/audio-shm.cpp',
   '../common/configuration.cpp',
+  '../common/linking.cpp',
   '../common/plugins.cpp',
   '../common/process.cpp',
   '../common/utils.cpp',

src/plugin/utils.cpp

@@ -19,7 +19,6 @@
 #include <iostream>
 
 #include <unistd.h>
-#include <boost/dll/runtime_symbol_info.hpp>
 #include <sstream>
 
 // Generated inside of the build directory
@@ -28,6 +27,9 @@
 #include "../common/configuration.h"
 #include "../common/utils.h"
 
+// FIXME: This should be passed as an argument instead
+#include "../common/linking.h"
+
 namespace fs = ghc::filesystem;
 
 // These functions are used to populate the fields in `PluginInfo`. See the
@@ -271,25 +273,6 @@ std::variant<OverridenWinePrefix, fs::path, DefaultWinePrefix> find_wine_prefix(
     return dosdevices_dir->parent_path();
 }
 
-fs::path get_this_file_location() {
-    // HACK: Not sure why, but `boost::dll::this_line_location()` returns a path
-    //       starting with a double slash on some systems. I've seen this happen
-    //       on both Ubuntu 18.04 and 20.04, but not on Arch based distros.
-    //       Under Linux a path starting with two slashes is treated the same as
-    //       a path starting with only a single slash, but Wine will refuse to
-    //       load any files when the path starts with two slashes. The easiest
-    //       way to work around this if this happens is to just add another
-    //       leading slash and then normalize the path, since three or more
-    //       slashes will be coerced into a single slash.
-    // FIXME: Replace Boost.Filesystem usage
-    fs::path this_file = boost::dll::this_line_location().string();
-    if (this_file.string().starts_with("//")) {
-        this_file = ("/" / this_file).lexically_normal();
-    }
-
-    return this_file;
-}
-
 bool equals_case_insensitive(const std::string& a, const std::string& b) {
     return std::equal(a.begin(), a.end(), b.begin(),
                       [](const char& a_char, const char& b_char) {

src/plugin/utils.h

@@ -235,12 +235,6 @@ ghc::filesystem::path generate_group_endpoint(
  */
 std::vector<ghc::filesystem::path> get_augmented_search_path();
 
-/**
- * Return a path to this `.so` file. This can be used to find out from where
- * this link to or copy of `libyabridge-{vst2,vst3}.so` was loaded.
- */
-ghc::filesystem::path get_this_file_location();
-
 /**
  * Load the configuration that belongs to a copy of or symlink to
  * `libyabridge-{vst2,vst3}.so`. If no configuration file could be found then